LUDINGTON, Mich. (CBS) — As of midday Thursday, a Michigan couple promoting awareness of postpartum depression were 41 miles into their swim across Lake Michigan.

As WBBM Newsradio’s Nancy Harty reports, Sarah and Jeff Tow have been at it since 7:50 a.m. Tuesday. They are swimming from Two Rivers, Wis., to the Big Point Sable Lighthouse in Ludington State Park on the west coast of Michigan.

Their mission is to become the first married couple to swim the 50 miles across Lake Michigan.

The Grand Rapids-area couple had been looking for a window of 48 hours of decent conditions. Family spokesman Ryan Reed says they hope to complete the swim in 30 to 36 hours, which would put them in Ludington on Wednesday afternoon or night.

The pair were on the swim team in Ohio University, and have been training for the ultra-marathon effort.

Training has included swims of five, 10 and more than 20 miles.

The Tows both suffered from postpartum depression when their children, ages 11 and 9, were born. They are trying to raise awareness.

LISTEN: WBBM Newsradio’s Nancy Harty reports

(TM and © Copyright 2012 CBS Radio Inc. and its relevant subsidiaries. CBS Radio and EYE Logo TM and Copyright 2012 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed. The Associated Press contributed to this report.)

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